CNG Hose -- What Pressure?

[Dancrosswis]

I've acquired an '86 C34 with a CNG tank.  The tank to stove hose looks to be original, i.e. time to be replaced.  The tank regulators are not vented to the outside.  I'm sourcing CNG hose.  Am I right that the regulator to stove hose can be low pressure, but the vent hose should be high pressure?

Any help will be kindly received.

Dan Cross
#159, Ennui Went

[KWKloeber]

I've acquired an '86 C34 with a CNG tank.  The tank to stove hose looks to be original, i.e. time to be replaced.  The tank regulators are not vented to the outside.  I'm sourcing CNG hose.  Am I right that the regulator to stove hose can be low pressure, but the vent hose should be high pressure?

Any help will be kindly received.

Dan Cross
#159, Ennui Went

You're talking about vent hose from the tank 'box' to a thruhull/overboard bulkhead fitting?

k

[KWKloeber]

I've acquired an '86 C34 with a CNG tank.  The tank to stove hose looks to be original, i.e. time to be replaced.  The tank regulators are not vented to the outside.  I'm sourcing CNG hose.  Am I right that the regulator to stove hose can be low pressure, but the vent hose should be high pressure?

Any help will be kindly received.

Dan Cross
#159, Ennui Went

You're talking about vent hose from the tank 'box' to a thruhull/overboard bulkhead fitting?

k

Mea culpa.  You said CNG, not LP!!!! Duh.

Tank is below? CNG doesn't need to be vented overboard as it's less dense than air.

k

[Dancrosswis]

Good save, K.  You're right, it's CNG.  The hose looks to attach directly to the regulator.  I'll run it from there to overboard.  I haven't figured out where that will be.  I'd be happy to get suggestions on where to locate the overboard vent fitting.

Dan

[KWKloeber]

Good save, K.  You're right, it's CNG.  The hose looks to attach directly to the regulator.  I'll run it from there to overboard.  I haven't figured out where that will be.  I'd be happy to get suggestions on where to locate the overboard vent fitting.

Dan

Dan,

I've not seen a CNG like that -- the 34 I chartered had no place that I saw for a line like that (was under the quarter berth.)  Pictures?

Ken

[Dancrosswis]

Sorry, I'm away from the boat and don't have any photos.  The tank is in the seat locker in the aft cabin.  I believe a vent hose was never installed and suspect that was standard.  My surveyor said it would be wise to install the vent hose.  If one of the regulators blows, it could put out a lot of CNG, which would take time to clear out of the boat on its own.  I suspect that I'll try to terminate the vent at the stern, to keep it out of the waves.

Dan

[Ralph Masters]

I would take it aft and up as high as you can and put in a vent similar to the fuel tank vent

[KWKloeber]

I believe a vent hose was never installed and suspect that was standard. 

Dan

Dunno where you are -- are you able to get CNG refilled -- it's becoming more of a PITA when I investigated installing it.

Does any C34 owner w/ CNG have a vented regulator? 
Standard - I've not heard that - as I said the 'standard 34' we chartered had no such vent.

Maybe RC / MaineSail can chime in here? Or, drop him a Q? on his SBO "ask questions here" forum.

Where does a vent hose attach to the reg that you have?  I have looked up pix of a dozen CNG regs and see none that have a 'vent' connection.

Do regs fail such that high pressure gas "leak's" into the appliance supply hose -- then a vent hose is useless. 
Or do they "blow" - I have not known one to do that.
Certainly no expert on CNG and other regulators, but have had many LP regulators over decades and grandfather had regs on two dozen LP tanks for cabins for 40 years.  I'm not sure how a regulator fails - and yet ensure that vented CNG would fail safe end up in a vent hose? 

Was that recommendation in the report or verbal?  Myself would be questioning the surveyor on how/what/why and assess what his "common sense" level is.  Ask what other mfgr does this so that you can look at the install.  If he can't in writing state what USCG/or other no. the vent hose has to meet, take it for what it's worth.

Those who can, do.  Those who can't, teach.  Those who can't do either, survey.   


Ken

[Noah]

I believe Stu uses CNG?

[Ed Shankle]

I have CNG. Luckily one of the boat yards on our harbor carries replacement tanks.
My tank is also located under the seat in the stern berth. There is a vent hose that runs from the regulator aft under the berth platform and into the open end of a ventilation tube that runs up to the vent housing on deck, starboard side. The hose runs along the inside of the tube, probably a couple of feet, up to the point that the tube turns up towards the vent housing. I don't know offhand what type of hose it is, but I don't recall it being the same as the high pressure hose between the tank and the stove.
Hope that helps,
Ed

[Stu Jackson]

Yes, Noah, we do.  Got the same comment from the surveyor, never did it, but if we did, I'd run it back and tuck it inside the blower hose connected to the starboard clamshell vent.  The boat's been running 29 years without it.  For replacement I'd use the same hose that goes to the stove, because it's a vent with an open end, no extra pressure.

[Dancrosswis]

Thanks for all the replies, especially those describing their hose runs.  My surveyor (whom I like and listen to) just added the hose recommendation orally.  In truth, it was in response to my prompts.  He knows I'm a putzer and would be happy with another project.

I will try to send a couple of photos of my regulators in the next post.  I have a screwdriver stuck in the "vent" outlet on the second regulator.  The outlet to the stove is hidden below the vent outlet in the photo.  I took a closer look at the vent hose running from the first to the second regulator.  It's marked Safgas CNG 50 psi Max.  So, with that, and the replies above, I feel comfortable installing a low pressure vent hose.

As to Wisconsin and CNG.  First, I don't have a lot of experience with CNG, so my knowledge is limited.  I've not found an exchange location in Wisconsin.  I was able to swap out my original tank for a recently certified tank at Larsen Marine in Waukegan, IL.  Fortunately, a Wisconsin oil company has installed CNG at a few stations in my area.  One is in Green Bay, which is en route to my boat, and one in Marinette, within a few miles of my slip.  So, this week I'm sourcing online and locally parts for a CNG fill adapter along the lines described by Steverhnm at http://shar.es/1fDgGl.  My tank swap was surprisingly expensive.  Though, in fairness to them, Larsen took a tank in rough shape and with no visible certification marks.  I'm looking forward to cheap refills at the pump.

Thanks again for all of the replies.

Dan

[Dancrosswis]

Sorry,  I can't figure out how to make my photos small enough to attach.  And, I've got to run out to buy some high pressure hydraulic fittings for my adapter.  What fun!

Dan

[Stu Jackson]

Sorry,  I can't figure out how to make my photos small enough to attach. 

Dan,

From the "101 Topics" sticky:

Posting Photos 101  http://c34.org/bbs/index.php/topic,3701.0.html